Treesearch

Trends in snow acidity reflect the balance between strong acid inputs and reactions with neutralizing materials. Carbonate dust can be an important contributor of buffering capacity to snow; however, its concentration in snow is difficult to quantify because it dissolves rapidly in snowmelt. In snow with neutral or acidic pH, most calcite would dissolve during sample melting if snow samples were processed using standard techniques. Here a method is described for separating particulate carbonate matter from snow. Snow samples were melted in solutions close to saturation with calcite,...

The MAGIC model (Cosby et al. 1985, 1986) was calibrated for East and West Glacier Lakes, two adjacent high-altitude (3200 m- 3700 m) catchments in the Medicine Bow National Forest of southern Wyoming. This model uses catchment characteristics including weathering rates, soil chemical characteristics, hydrological parameters, and precipitation amounts and composition to calculate simulated lake and stream chemistry. The simulations suggest that if precipitation were acidified to pH 4.27 with sulfuric acid, the ANC of the lakes would rapidly drop by about 30 meq/m3 . This rapid drop would...

We characterized spawning sites of Yellowstone cutthroat trout Oncorhynchus clarki bouvieri, described the microhabitat of completed redds, and tested the influence of habitat conditions on the morphology of completed redds in Pine Creek, Idaho. Cutthroat trout spawned in June as flows subsided after peak stream discharge. During spawning, minimum and maximum water temperatures ranged 4-9°C and 16-20°C, respectively. Trout spawned where water depths averaged 20 cm beside redds and 22 cm upstream of redds. Water velocities averaged 42 cm/s beside redds and 46 cm/s upstream of redds. More...

Fisheries resources are finite and conflicts may arise when several groups compete for the same resource. Diverse groups of anglers often derive different benefits and possess different preferences concerning the way a resource should be managed. This paper examines the conflict which arose when new regulations were proposed for reaches of ldaho's Big Wood River. One organized group of anglers lobbied for specific restrictive regulations. Another group of anglers responded and successfully challenged the new regulations in court. We describe factors contributing to the controversy and...

Experimental burns were conducted on 36 plots in mixed conifer logging slash in northern Idaho, under varying fuel loadings and moisture conditions. This paper reports the immediate effects of these burns on the forest floor, the woody fuel complex, and the plant community, and includes recommendations to managers for using prescribed fire in this forest type. Much of the shallow layer of duff was consumed exposing mineral soil under the full range of burn conditions; however, the deep pockets of rotten wood in the forest floor retained moisture throughout the burning season, and were...

Temperature measurements were made to better understand the role of microclimate on mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae), activity as a result of thinning lodgepole pine stands. Sampling was done over 61 days on the north slope of the Unita Mountain Range in northeastern Utah. Principal components analysis was applied to all temperature variables. Most of the variation was attributed to two variables, coolest part of the night and hottest part of the day. The thinned stand was approximately 1 °C warmer than the unthinned stand. Day temperature was...

Annual weeds continue to expand throughout the West eliminating many desirable species and plant communities. Wildfires are now common on lands infested with annual weeds, causing a loss of wildlife habitat and other natural resources. Measures can be used to reduce burning and restore native plant communities, but restoration is difficult and costly.

Experiments were conducted to determine speed of action and toxicities of extracts of Tagetes minuta L., a source of naturally occurring insecticidal compounds. LC50 values for male and female Mexican bean weevils, Zabrotes subfasciatus (Boheman), were determined for floral, foliar, and root extracts of T. minuta. The 24-h LC50 values ranged from 138 μ g/cm2 for males exposed to the root extract (most susceptible) to 803 μ g/cm2 for females exposed to the foliar extract (least susceptible). Increasing the duration of exposure to 48 h decreased all LC50 values 20-30 μ g/cm2. Males were more...

This conference brought together scientiests and managers from federal, state, and local agencies, along with private-sector interests, to examine key concepts involving sustainable ecological systems, and ways in which to apply these concepts to ecosystem management. Session topics were: ecological consequenses of land and water use changes, biology of rare and declining species and habitats, conservation biology and restoration ecology, developing and applying ecological theory to management of ecological systems, sustainable ecosystems and forest health, and sustainable ecosystems to...

Many species of songbirds have experienced population declines in the eastern U.S. in recent years, but conclusive data on population trends and factors affecting populations in the West are lacking. Few studies have evaluated the importance of surrounding land configuration to songbird abundances. In 1992, we initiated a study in mixed conifer forest in west-central Idaho to compare songbird composition and abundances among two untreated watersheds and three watersheds having clearcuts. Watersheds were selected on the basis of their la-rge size, accessibility, dominant tree type, and...